# Private MCP result is reused across authorization contexts

A shared cache delivers caller-specific protocol data outside the authorization context that produced it.

**Candidate CWE:** [CWE-524](https://cwe.mitre.org/data/definitions/524.html) · [CWE-863](https://cwe.mitre.org/data/definitions/863.html)

## Test hypothesis

Warm a private owned B resource; repeat the same operation as A and compare with cold-cache denial. Separately inspect whether state-bearing MRTR retry results are incorrectly cached.

## Evidence required

Record method/parameters, authorization-context fingerprints, cache hints, cache hit/miss and the newly exposed private marker.

## Rule out false positives

Identical public tool lists, hints without a demonstrated shared result, or private content legitimately accessible to both callers do not prove exposure.

## Playbook and command references

- [AI state: memory, resumed work, retries and private caches](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/modules/ai-state-lifecycle.html) — Test persistent context, task ownership, MCP request-state integrity, duplicate effects and caches across identities and time.
- [RAG isolation: ingestion, retrieval, citations and revocation](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/modules/rag-tenant-isolation.html) — Trace document authorization through vector search, generated answers, citation downloads, caches and sharing changes.

[Find the associated command snippets](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/commands.html?q=AI%20state%3A%20memory%2C%20resumed%20work%2C%20retries%20and%20private%20caches)

## Referenced by these target playbooks

[AI, agents & MCP](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/ai.html) · [OSS & self-hosted](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/oss.html)

## Report checklist

- [ ] Capture the affected version, configuration, identities, and object ownership.
- [ ] Preserve a valid baseline and a negative control.
- [ ] Reproduce the forbidden data access, action, or state change on controlled fixtures.
- [ ] Explain the intended security rule and why the observed behavior violates it.
- [ ] State prerequisites, uncertainty, cleanup, and the smallest demonstrated impact.

## Conditional ATT&CK mapping

No direct ATT&CK mapping selected. Record the weakness and demonstrated impact without forcing an adversary-behavior classification. See the [mapping guide](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/attack.html).

## Primary references

- [MCP 2026-07-28 caching](https://modelcontextprotocol.io/specification/2026-07-28/server/utilities/caching)

[Back to the complete vulnerability catalog](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/vulnerabilities.html)